Techniques are known in the domain of integrated circuits using calculation units for verifying if the format allowed for the result of an arithmetic operation carried out by an AU (Arithmetic Unit) on two operands A and B and an input carry digit Cin does not exceed a given format. This technique has applications in most calculation units, such as, calculation units included in programmable circuits, such as, a digital signal processor (DSP) or a microcontroller. When it does, an "overflow beyond n bits" occurs and in this case a result saturation may be applied. In general, this type of overflow is determined after the result has been determined, that is, when the AU has finished processing of operands A and B and the input carry digit Cin. In other words, considering FIG. 1 which schematically shows the various processing steps between when operands A and B and the input carry digit Cin are input into the AU, and when the result S is written in the accumulator, the determination of an overflow is classically done after the calculation step E.sub.2.
Therefore, to determine if an overflow has occurred, it is necessary to wait until the AU has finished the calculation. In this case there is a time loss that is particularly long if the calculation done by the AU is complex.